--- old/src/share/classes/java/util/concurrent/PriorityBlockingQueue.java Wed Jun 27 01:16:26 2012 +++ new/src/share/classes/java/util/concurrent/PriorityBlockingQueue.java Wed Jun 27 01:16:22 2012 @@ -35,7 +35,8 @@ package java.util.concurrent; -import java.util.concurrent.locks.*; +import java.util.concurrent.locks.Condition; +import java.util.concurrent.locks.ReentrantLock; import java.util.*; /** @@ -111,7 +112,7 @@ * java.util.PriorityQueue operations within a lock, as was done * in a previous version of this class. To maintain * interoperability, a plain PriorityQueue is still used during - * serialization, which maintains compatibility at the espense of + * serialization, which maintains compatibility at the expense of * transiently doubling overhead. */ @@ -308,14 +309,13 @@ /** * Mechanics for poll(). Call only while holding lock. */ - private E extract() { - E result; + private E dequeue() { int n = size - 1; if (n < 0) - result = null; + return null; else { Object[] array = queue; - result = (E) array[0]; + E result = (E) array[0]; E x = (E) array[n]; array[n] = null; Comparator cmp = comparator; @@ -324,8 +324,8 @@ else siftDownUsingComparator(0, x, array, n, cmp); size = n; + return result; } - return result; } /** @@ -382,39 +382,43 @@ */ private static void siftDownComparable(int k, T x, Object[] array, int n) { - Comparable key = (Comparable)x; - int half = n >>> 1; // loop while a non-leaf - while (k < half) { - int child = (k << 1) + 1; // assume left child is least - Object c = array[child]; - int right = child + 1; - if (right < n && - ((Comparable) c).compareTo((T) array[right]) > 0) - c = array[child = right]; - if (key.compareTo((T) c) <= 0) - break; - array[k] = c; - k = child; + if (n > 0) { + Comparable key = (Comparable)x; + int half = n >>> 1; // loop while a non-leaf + while (k < half) { + int child = (k << 1) + 1; // assume left child is least + Object c = array[child]; + int right = child + 1; + if (right < n && + ((Comparable) c).compareTo((T) array[right]) > 0) + c = array[child = right]; + if (key.compareTo((T) c) <= 0) + break; + array[k] = c; + k = child; + } + array[k] = key; } - array[k] = key; } private static void siftDownUsingComparator(int k, T x, Object[] array, int n, Comparator cmp) { - int half = n >>> 1; - while (k < half) { - int child = (k << 1) + 1; - Object c = array[child]; - int right = child + 1; - if (right < n && cmp.compare((T) c, (T) array[right]) > 0) - c = array[child = right]; - if (cmp.compare(x, (T) c) <= 0) - break; - array[k] = c; - k = child; + if (n > 0) { + int half = n >>> 1; + while (k < half) { + int child = (k << 1) + 1; + Object c = array[child]; + int right = child + 1; + if (right < n && cmp.compare((T) c, (T) array[right]) > 0) + c = array[child = right]; + if (cmp.compare(x, (T) c) <= 0) + break; + array[k] = c; + k = child; + } + array[k] = x; } - array[k] = x; } /** @@ -520,13 +524,11 @@ public E poll() { final ReentrantLock lock = this.lock; lock.lock(); - E result; try { - result = extract(); + return dequeue(); } finally { lock.unlock(); } - return result; } public E take() throws InterruptedException { @@ -534,7 +536,7 @@ lock.lockInterruptibly(); E result; try { - while ( (result = extract()) == null) + while ( (result = dequeue()) == null) notEmpty.await(); } finally { lock.unlock(); @@ -548,7 +550,7 @@ lock.lockInterruptibly(); E result; try { - while ( (result = extract()) == null && nanos > 0) + while ( (result = dequeue()) == null && nanos > 0) nanos = notEmpty.awaitNanos(nanos); } finally { lock.unlock(); @@ -559,13 +561,11 @@ public E peek() { final ReentrantLock lock = this.lock; lock.lock(); - E result; try { - result = size > 0 ? (E) queue[0] : null; + return (size == 0) ? null : (E) queue[0]; } finally { lock.unlock(); } - return result; } /** @@ -649,32 +649,28 @@ * @return {@code true} if this queue changed as a result of the call */ public boolean remove(Object o) { - boolean removed = false; final ReentrantLock lock = this.lock; lock.lock(); try { int i = indexOf(o); - if (i != -1) { - removeAt(i); - removed = true; - } + if (i == -1) + return false; + removeAt(i); + return true; } finally { lock.unlock(); } - return removed; } - /** * Identity-based version for use in Itr.remove */ - private void removeEQ(Object o) { + void removeEQ(Object o) { final ReentrantLock lock = this.lock; lock.lock(); try { Object[] array = queue; - int n = size; - for (int i = 0; i < n; i++) { + for (int i = 0, n = size; i < n; i++) { if (o == array[i]) { removeAt(i); break; @@ -694,15 +690,13 @@ * @return {@code true} if this queue contains the specified element */ public boolean contains(Object o) { - int index; final ReentrantLock lock = this.lock; lock.lock(); try { - index = indexOf(o); + return indexOf(o) != -1; } finally { lock.unlock(); } - return index != -1; } /** @@ -728,7 +722,6 @@ } } - public String toString() { final ReentrantLock lock = this.lock; lock.lock(); @@ -739,7 +732,7 @@ StringBuilder sb = new StringBuilder(); sb.append('['); for (int i = 0; i < n; ++i) { - E e = (E)queue[i]; + Object e = queue[i]; sb.append(e == this ? "(this Collection)" : e); if (i != n - 1) sb.append(',').append(' '); @@ -757,23 +750,7 @@ * @throws IllegalArgumentException {@inheritDoc} */ public int drainTo(Collection c) { - if (c == null) - throw new NullPointerException(); - if (c == this) - throw new IllegalArgumentException(); - final ReentrantLock lock = this.lock; - lock.lock(); - try { - int n = 0; - E e; - while ( (e = extract()) != null) { - c.add(e); - ++n; - } - return n; - } finally { - lock.unlock(); - } + return drainTo(c, Integer.MAX_VALUE); } /** @@ -792,11 +769,10 @@ final ReentrantLock lock = this.lock; lock.lock(); try { - int n = 0; - E e; - while (n < maxElements && (e = extract()) != null) { - c.add(e); - ++n; + int n = Math.min(size, maxElements); + for (int i = 0; i < n; i++) { + c.add((E) queue[0]); // In this order, in case add() throws. + dequeue(); } return n; } finally { @@ -844,8 +820,7 @@ * The following code can be used to dump the queue into a newly * allocated array of {@code String}: * - * 
-     *     String[] y = x.toArray(new String[0]);
+ * 
 {@code String[] y = x.toArray(new String[0]);}
* * Note that {@code toArray(new Object[0])} is identical in function to * {@code toArray()}. @@ -898,7 +873,7 @@ */ final class Itr implements Iterator { final Object[] array; // Array of all elements - int cursor; // index of next element to return; + int cursor; // index of next element to return int lastRet; // index of last element, or -1 if no such Itr(Object[] array) { @@ -926,17 +901,18 @@ } /** - * Saves the state to a stream (that is, serializes it). For - * compatibility with previous version of this class, - * elements are first copied to a java.util.PriorityQueue, - * which is then serialized. + * Saves this queue to a stream (that is, serializes it). + * + * For compatibility with previous version of this class, elements + * are first copied to a java.util.PriorityQueue, which is then + * serialized. */ private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException { lock.lock(); try { - int n = size; // avoid zero capacity argument - q = new PriorityQueue(n == 0 ? 1 : n, comparator); + // avoid zero capacity argument + q = new PriorityQueue(Math.max(size, 1), comparator); q.addAll(this); s.defaultWriteObject(); } finally { @@ -946,10 +922,7 @@ } /** - * Reconstitutes the {@code PriorityBlockingQueue} instance from a stream - * (that is, deserializes it). - * - * @param s the stream + * Reconstitutes this queue from a stream (that is, deserializes it). */ private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {